This magnetic stirrer makes performing water tests easier.  Charge it with a USB cable, and stop manually shaking vials as you add drop after drop.  

• Compact Design
• USB Rechargeable Battery (USB 5v)
• Low Battery Indicator
• Auto Power Off Function (5 minutes)
• Compatible with most standard test kits

Charging time: 120 minutes
Holds 27mm vials or smaller (RedSea, Elos)
Includes micro USB cable and stirring bar